Miele Freezer Error Code F120

F120 indicates that the freezer's internal monitoring system detected incoming AC voltage below 85 volts AC. This is a supply voltage fault rather than a failure of a refrigeration component. The code is stored internally and is not displayed on the customer-facing panel, so it is typically found only during a technician's diagnostic session.

Operating any appliance on a chronically low voltage supply can stress the compressor motor and shorten its service life. If the voltage is frequently dropping below 85VAC, continued operation risks damaging internal components over time. It is best to identify and correct the voltage supply issue before relying on the unit long-term.

A reset may clear the stored fault code temporarily, but if the underlying low voltage condition persists, F120 will be logged again. Because this code is not visible on the customer display, you may not see it return without another diagnostic scan. Clearing the code without fixing the supply voltage issue does not resolve the problem.

If the cause is an overloaded circuit, extension cord, or loose outlet connection, a knowledgeable homeowner may be able to address those issues directly. However, measuring actual supply voltage under load and inspecting wiring inside junction boxes should be handled by a qualified electrician or appliance technician. If the control board is at fault, a professional repair is required.

If the fix involves only electrical work at the outlet or circuit, costs can range from around $75 to $250 depending on what is needed. If the control board must be replaced, parts and labor for a Miele unit typically range from $300 to $600 or more. Having a technician confirm the root cause first helps avoid unnecessary parts replacement.